Combustor basket cooling ring

ABSTRACT

A cooling ring (102) of a combustor basket system (110) has a transition zone 108 that extends to a cooling channel (106) at a cooling channel entrance (104). The transition zone (108) has the substantially the same material strength throughout the length of the transition zone (108). By having the same material strength throughout the length of the transition zone (108), the cooling ring (102) is able to withstand greater stresses than previously used cooling rings. One way in which this is accomplished is by having a uniform thickness.

BACKGROUND 1. Field

Disclosed embodiments are generally related to combustors and, moreparticularly to cooling rings used with combustor baskets.

2. Description of the Related Art

Cooling rings used with combustor baskets typically require reduction ofthe outer diameter of the cooling ring just before an entrance into acooling channel. The diameter of the cooling ring is reduced by reducingthe material thickness of the cooling ring. The reduction of the outerdiameter occurs due to manufacturing needs and to provide the coolingair with a smooth entrance to the combustor basket's cooling channels.

FIG. 1 shows a standard combustor basket system 10 that uses a typicalcooling ring 2. In FIG. 1 the cooling ring 2 is cylindrical shaped. Thecooling ring 2 has an outer diameter D₁ throughout a majority of itslength. Prior to a cooling channel entrance 4 of a cooling channel 6 isa transition zone 8, which begins at transition zone start 11 and endsat transition zone end 13. Transition zone end 13 is located at thecooling channel entrance 4. The transition zone 8 has a wall 3, whichhas an inner surface 5 and outer surface 7. The transition zone 8 has anouter diameter D₁ that is reduced to an outer diameter D₂ as itapproaches the transition zone end 13 and the cooling channel entrance4. D₂ is the outer diameter of the cooling ring 2 at a portion of thetransition zone 8. This reduction to outer diameter D₂ is due toreduction of the material thickness of the cooling ring 2 at thetransition zone 8. This is done so that flow of air remains beneficialfor the combustor basket system 10.

The reduction of the outer diameter D₁ to the outer diameter D₂ of thecooling ring 2 prior to the entrance to the cooling channel 6 reducesthe thickness T₁ of the cooling ring 2. The reduction of the thicknessT₁ of the cooling ring 102 results in reduction of the material strengthin that area, leading to a reduction in low cycle fatigue life.

FIGS. 2A and 2B illustrate the stresses that occur with the cooling ring2. FIG. 2A depicts the temperatures that impact the cooling ring 2. FIG.2B illustrates the Von Mises stresses that occur within the cooling ring2 due to the effect of the temperatures. As shown in FIG. 2B, the VonMises stresses are greater at the location of the cooling ring 2 wherethe outer diameter D₁ is reduced to the outer diameter D₂ and wherethere is reduction of the thickness T₁ of wall 3.

In the past to address this problem the temperature of the cooling ringin the weakened area was reduced. Reducing the temperature limited thestresses that occur at the area to an acceptable value, however wouldrequire trade-offs to other aspects of the combustor basket system.

SUMMARY

Briefly described, aspects of the present disclosure relate to coolingrings used in combustor basket systems.

A first aspect of the disclosure provides a combustor basket systemhaving a cooling ring comprising a transition zone, wherein thetransition zone extends from a transition zone start to a coolingchannel entrance. The combustor basket system also comprises atransition zone that has a cross-section profile configured to provide asubstantially uniform material strength.

A second aspect of the disclosure provides a cooling ring for use with acombustor basket system. The cooling ring comprises a wall having anouter surface and an inner surface. The wall forms a transition zonethat extends to a cooling channel entrance of the basket cooling system.The wall has a thickness which is the distance between the outer surfaceand the inner surface and further wherein the material strength of thewall is substantially uniform throughout the transition zone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is cross-sectional side view of a combustor basket system thatuses a prior art cooling ring.

FIG. 2A shows a diagram illustrating the temperatures that affect thecooling ring shown in FIG. 1.

FIG. 2B shows a diagram illustrating the Von Mises stresses that occurwith the cooling ring shown in FIG. 1.

FIG. 3 is a cross-sectional side view of a combustor basket system thatuses a cooling ring in accordance with an embodiment of the presentdisclosure.

FIG. 4A shows a diagram illustrating the temperatures that affect thecooling ring shown in FIG. 3.

FIG. 4B shows a diagram illustrating the Von Mises stresses that occurwith the cooling ring show in FIG. 3.

DETAILED DESCRIPTION

To facilitate an understanding of embodiments, principles, and featuresof the present disclosure, they are explained hereinafter with referenceto implementation in illustrative embodiments. Embodiments of thepresent disclosure, however, are not limited to use in the describedsystems or methods.

The components and materials described hereinafter as making up thevarious embodiments are intended to be illustrative and not restrictive.Many suitable components and materials that would perform the same or asimilar function as the materials described herein are intended to beembraced within the scope of embodiments of the present disclosure.

To ameliorate the problems that occur due to the reduction in thethickness of the cooling ring 2 shown in FIG. 1, an embodiment of thepresent disclosure has the location of the entrance to cooling channelsnot at a cylindrical section of a combustor, but instead locates theentrance to the cooling channels at a conical section of a combustorbasket system. By moving the transition zone and entrance to a conicalsection of the of the combustor basket system, the machined feature ofthe cooling ring 2 that results in a weakness is eliminated and thethickness of the cooling ring can be maintained throughout its length.This also provides the benefit of being able to use fewer liners than inprevious combustor basket systems.

Referring to FIG. 3, wherein an embodiment of the present inventionshown, a cooling ring 102 is shown used in combustor basket system 110.The combustor basket system 110 shown in FIG. 3 is colloquially referredto as a G-type basket style system. By “G-type basket style” it is meantthe basket is used with a G-frame combustor. With a G-type basket stylethe active combustion length is split between 25% being the combustorbasket and 75% the transition zone. In other words, the transition zoneis longer than the combustor basket. In other types of combustor basketsystems, the active combustion length is generally split between thecombustor basket and the transition zone so that it is 50% combustorbasket and 50% transition zone. While, the combustor basket system 110shown in FIG. 3 is a G-type basket style, it is contemplated that othertypes of styles may be employed. For example, the cooling ring 102 maybe employed with baskets colloquially referred to as “D-type,” “E-type,”“F-type”, “H-type baskets” and “J-type baskets.”

Still referring to FIG. 3, the cooling ring 102 is formed by a wall 103that has an inner surface 105 and an outer surface 107 and formstransition zone 108. In the embodiment shown in FIG. 3, the cooling ring102 is conically shaped. However it should be understood that othershapes may be accommodated provided that the cooling ring 102 is able tomaintain its material strength at the transition zone 108. By “materialstrength” it is meant that that the stresses that the material is ableto withstand due to environmental factors, such as forces impacting thematerial or temperatures that the material can withstand withoutfailure. The limiting factor of cooling rings is low cycle fatigue lifewhich is impacted by material properties and the temperature.

The transition zone 108 is the portion of the cooling ring 102 thatbegins at transition zone start 111 and ends at transition zone end 113.Transition zone start 111 may be the area where the cooling ring 102begins, or alternatively an area proximate to where the cooling ring 102begins. The transition zone start 111 may also begin prior to the hotsection of the combustor basket system 110, however the transition zonestart 111 may be located after another cooling feature of the combustorbasket system 110. Transition zone end 113 is that area of thetransition zone 108 where the cooling channel entrance 104 begins. Thetransition zone 108 may be 75% of the length of the active combustionlength, which is defined as the length of the combustor in whichcombustion occurs.

The cooling ring 102 may be made of nickel alloys with high nickelconcentrations, or other materials capable of withstanding temperaturesfound within combustor basket system 110. Generally speaking thetemperatures that the cooling ring 102 can withstand in the transitionzone 108 are temperatures within the range of 500 to 1000° C., morepreferably the cooling ring 102 can withstand temperatures greater than700° C.

The transition zone 108 of the cooling ring 102 is able to withstandtemperatures greater than 750° C. without having to provide additionalmeasures to cool the area in the transition zone 108, such as thoserequired in typical combustor basket systems. In some embodiments thismeans that the number of air holes 117 located in the combustor basketsystem 110 may be reduced. For example the number of air holes used inprevious combustor basket systems may be greater than 180. In combustorbasket system 110 the number of air holes 117 may be less than 180 andmay be as low as 90, or less.

Still referring to FIG. 3, the combustor basket system 110 has a coolingchannel entrance 104 that permits access of cooling air into a coolingchannel 106. In an embodiment of the present invention, the outerdiameter D₃ of the cooling ring 102 gradually increases, to the diameterD₄ as it approaches cooling channel entrance 104. The gradual increasemay be accomplished by having an angle α that is less than about 10° butgreater than 3°, and more preferably from between about 4-6°. The angleα is an angle that is formed between a point on the horizontal lineformed by the central axis of the cooling basket system 110 and a pointon the inner surface 105 of the wall 103.

While the outer diameter of the cooling ring 102 gradually increases,the thickness T₂ of the cooling ring 102 may remain substantiallyconstant, that is within appropriate manufacturing tolerances. Thethickness T₂ is the distance between the outer surface 107 and the innersurface 105 of the wall 103 of the cooling ring 102. Thus the transitionzone 108 has substantially the same thickness T₂ throughout. Preferablythe thickness T₂ is between 4 to 12 mm and more preferably between 5-8mm, while it is contemplated that a uniform thickness extends throughoutthe transition zone 108, it should be understood that preferably thethickness is such that the integrity of the cooling ring 102 is notcompromised during use due to material weaknesses, or that the Von Misesstresses that affect the cooling ring 102 are such that they do notadversely impact the cooling ring 102 in a particular location. In otherwords, maintaining the thickness T₂ constant throughout the transitionzone 108 is one way in which material weaknesses do not adversely impactone particular area of the cooling ring 102. Other features of thecooling ring 2, discussed herein, may also provide ways in which thematerial strength of the cooling ring 2 may remain constant throughoutthe transition zone 108.

In an embodiment of the present disclosure, the transition zone 108 isintegrally formed as part of the cooling ring 102. However, thetransition zone 108 may also be formed from sheet metal and welded tothe cooling ring 102. By maintaining the thickness T₂ substantiallyconstant the weakness exhibited by typical cooling rings is avoidedbecause there is no change in the material thickness of the transitionzone 108 thereby maintaining a uniform material strength.

Additionally, the transition zone 108 approaches the cooling channelentrance 104 with a step-like feature having a having a height of Hi.The height Hi is the distance the cooling channel entrance 104 is abovethe outer surface 103. Hi may be between the ranges of 3 to 15 mm. Theheight Hi plays a beneficial role in the flow of air through thecombustor basket system 110.

FIGS. 4A and 4B illustrate representative stresses that may occur withthe cooling ring 102. FIG. 4A depicts the temperatures that impact thecooling ring 102. FIG. 4B illustrates representative Von Mises stressesthat occur within the cooling ring 102 due to the impact of thetemperature on the cooling ring 102. As shown in FIG. 4B, the Von Misesstresses are reduced at the cooling channel entrance 104, as comparedwith the cylindrical cooling ring 2, because there is no reduction inthe thickness T₂ of the cooling ring 102 at the cooling channel entrance104. Further, the angle and direction at which the transition zone 108meets the cooling channel entrance 104 permits there to be smooth flowof air. Further, as opposed to typical combustor basket systems, thenumber of liners 119 used in the system may be reduced.

While embodiments of the present disclosure have been disclosed inexemplary forms, it will be apparent to those skilled in the art thatmany modifications, additions, and deletions can be made therein withoutdeparting from the spirit and scope of the invention and itsequivalents, as set forth in the following claims.

1. A combustor basket system comprising: a cooling ring comprising atransition zone, wherein the transition zone extends from a transitionzone start to a cooling channel entrance; and wherein the transitionzone comprises a cross-section profile configured to provide asubstantially uniform material strength.
 2. The system of claim 1,wherein the transition zone has a uniform thickness.
 3. The system ofclaim 1, wherein the cooling ring is conical shaped.
 4. The system ofclaim 3, wherein the cooling ring can withstand temperaturessubstantially above 700 C.° without failure.
 5. The system of claim 4,wherein an outer diameter of the cooling ring is larger at a firstlocation of the transition zone than at another location of thetransition zone.
 6. The system of claim 5, wherein the outer diameter ofthe cooling ring is greatest closest to the cooling channel entrance. 7.The system of claim 1, wherein the basket cooling system has atransition zone that is 75% of an active combustion length.
 8. Thesystem of claim 1, wherein the transition zone has a step-like featureat the cooling channel entrance.
 9. The system of claim 1, wherein thereis an angle α that is between about 3 to 10°.
 10. The system of claim 9,wherein the thickness of the transition zone (108) is between 5-8 mm.11. A cooling ring for use with a basket cooling system comprising: awall having an outer surface and an inner surface; wherein the wallforms a transition zone that extends to a cooling channel entrance ofthe basket cooling system; wherein the wall has a thickness which is thedistance between the outer surface and the inner surface, and whereinthe material strength of the wall is substantially uniform throughoutthe transition zone.
 12. The cooling ring of claim 11, wherein the wallhas a uniform thickness.
 13. The cooling ring of claim 11, wherein thecooling ring (102) is conical shaped.
 14. The cooling ring of claim 11,wherein the cooling ring can withstand temperatures substantially above700 C.° without failure.
 15. The cooling ring of claim 11, wherein anouter diameter of the cooling ring is larger at a transition zone endthan at transition zone start.
 16. The cooling ring of claim 15, whereinthe outer diameter of the cooling ring is greatest closest to a coolingchannel entrance.
 17. The cooling ring of claim 11, wherein the basketcooling system has a transition zone that is 75% of an active combustionlength.
 18. The cooling ring of claim 11, wherein the transition zonehas a step-like feature located proximate to a cooling channel entrance.19. The cooling ring of claim 11, wherein there is an angle α that isbetween about 3 to 10°.
 20. The cooling ring of claim 11, wherein thethickness of the transition zone is between 5-8 mm.